FFmpeg
 All Data Structures Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
cdgraphics.c
Go to the documentation of this file.
1 /*
2  * CD Graphics Video Decoder
3  * Copyright (c) 2009 Michael Tison
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "avcodec.h"
23 #include "bytestream.h"
24 #include "internal.h"
25 
26 /**
27  * @file
28  * @brief CD Graphics Video Decoder
29  * @author Michael Tison
30  * @see http://wiki.multimedia.cx/index.php?title=CD_Graphics
31  * @see http://www.ccs.neu.edu/home/bchafy/cdb/info/cdg
32  */
33 
34 /// default screen sizes
35 #define CDG_FULL_WIDTH 300
36 #define CDG_FULL_HEIGHT 216
37 #define CDG_DISPLAY_WIDTH 294
38 #define CDG_DISPLAY_HEIGHT 204
39 #define CDG_BORDER_WIDTH 6
40 #define CDG_BORDER_HEIGHT 12
41 
42 /// masks
43 #define CDG_COMMAND 0x09
44 #define CDG_MASK 0x3F
45 
46 /// instruction codes
47 #define CDG_INST_MEMORY_PRESET 1
48 #define CDG_INST_BORDER_PRESET 2
49 #define CDG_INST_TILE_BLOCK 6
50 #define CDG_INST_SCROLL_PRESET 20
51 #define CDG_INST_SCROLL_COPY 24
52 #define CDG_INST_LOAD_PAL_LO 30
53 #define CDG_INST_LOAD_PAL_HIGH 31
54 #define CDG_INST_TILE_BLOCK_XOR 38
55 
56 /// data sizes
57 #define CDG_PACKET_SIZE 24
58 #define CDG_DATA_SIZE 16
59 #define CDG_TILE_HEIGHT 12
60 #define CDG_TILE_WIDTH 6
61 #define CDG_MINIMUM_PKT_SIZE 6
62 #define CDG_MINIMUM_SCROLL_SIZE 3
63 #define CDG_HEADER_SIZE 8
64 #define CDG_PALETTE_SIZE 16
65 
66 typedef struct CDGraphicsContext {
68  int hscroll;
69  int vscroll;
71 
73 {
75  frame->reference = 3;
80 }
81 
83 {
84  CDGraphicsContext *cc = avctx->priv_data;
85 
86  cdg_init_frame(&cc->frame);
87 
88  avctx->width = CDG_FULL_WIDTH;
89  avctx->height = CDG_FULL_HEIGHT;
90  avctx->pix_fmt = AV_PIX_FMT_PAL8;
91 
92  return 0;
93 }
94 
96 {
97  int y;
98  int lsize = cc->frame.linesize[0];
99  uint8_t *buf = cc->frame.data[0];
100  int color = data[0] & 0x0F;
101 
102  if (!(data[1] & 0x0F)) {
103  /// fill the top and bottom borders
104  memset(buf, color, CDG_BORDER_HEIGHT * lsize);
105  memset(buf + (CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT) * lsize,
106  color, CDG_BORDER_HEIGHT * lsize);
107 
108  /// fill the side borders
109  for (y = CDG_BORDER_HEIGHT; y < CDG_FULL_HEIGHT - CDG_BORDER_HEIGHT; y++) {
110  memset(buf + y * lsize, color, CDG_BORDER_WIDTH);
111  memset(buf + CDG_FULL_WIDTH - CDG_BORDER_WIDTH + y * lsize,
112  color, CDG_BORDER_WIDTH);
113  }
114  }
115 }
116 
117 static void cdg_load_palette(CDGraphicsContext *cc, uint8_t *data, int low)
118 {
119  uint8_t r, g, b;
120  uint16_t color;
121  int i;
122  int array_offset = low ? 0 : 8;
123  uint32_t *palette = (uint32_t *) cc->frame.data[1];
124 
125  for (i = 0; i < 8; i++) {
126  color = (data[2 * i] << 6) + (data[2 * i + 1] & 0x3F);
127  r = ((color >> 8) & 0x000F) * 17;
128  g = ((color >> 4) & 0x000F) * 17;
129  b = ((color ) & 0x000F) * 17;
130  palette[i + array_offset] = 0xFFU << 24 | r << 16 | g << 8 | b;
131  }
132  cc->frame.palette_has_changed = 1;
133 }
134 
136 {
137  unsigned ci, ri;
138  int color;
139  int x, y;
140  int ai;
141  int stride = cc->frame.linesize[0];
142  uint8_t *buf = cc->frame.data[0];
143 
144  ri = (data[2] & 0x1F) * CDG_TILE_HEIGHT + cc->vscroll;
145  ci = (data[3] & 0x3F) * CDG_TILE_WIDTH + cc->hscroll;
146 
147  if (ri > (CDG_FULL_HEIGHT - CDG_TILE_HEIGHT))
148  return AVERROR(EINVAL);
149  if (ci > (CDG_FULL_WIDTH - CDG_TILE_WIDTH))
150  return AVERROR(EINVAL);
151 
152  for (y = 0; y < CDG_TILE_HEIGHT; y++) {
153  for (x = 0; x < CDG_TILE_WIDTH; x++) {
154  if (!((data[4 + y] >> (5 - x)) & 0x01))
155  color = data[0] & 0x0F;
156  else
157  color = data[1] & 0x0F;
158 
159  ai = ci + x + (stride * (ri + y));
160  if (b)
161  color ^= buf[ai];
162  buf[ai] = color;
163  }
164  }
165 
166  return 0;
167 }
168 
169 #define UP 2
170 #define DOWN 1
171 #define LEFT 2
172 #define RIGHT 1
173 
174 static void cdg_copy_rect_buf(int out_tl_x, int out_tl_y, uint8_t *out,
175  int in_tl_x, int in_tl_y, uint8_t *in,
176  int w, int h, int stride)
177 {
178  int y;
179 
180  in += in_tl_x + in_tl_y * stride;
181  out += out_tl_x + out_tl_y * stride;
182  for (y = 0; y < h; y++)
183  memcpy(out + y * stride, in + y * stride, w);
184 }
185 
186 static void cdg_fill_rect_preset(int tl_x, int tl_y, uint8_t *out,
187  int color, int w, int h, int stride)
188 {
189  int y;
190 
191  for (y = tl_y; y < tl_y + h; y++)
192  memset(out + tl_x + y * stride, color, w);
193 }
194 
195 static void cdg_fill_wrapper(int out_tl_x, int out_tl_y, uint8_t *out,
196  int in_tl_x, int in_tl_y, uint8_t *in,
197  int color, int w, int h, int stride, int roll)
198 {
199  if (roll) {
200  cdg_copy_rect_buf(out_tl_x, out_tl_y, out, in_tl_x, in_tl_y,
201  in, w, h, stride);
202  } else {
203  cdg_fill_rect_preset(out_tl_x, out_tl_y, out, color, w, h, stride);
204  }
205 }
206 
208  AVFrame *new_frame, int roll_over)
209 {
210  int color;
211  int hscmd, h_off, hinc, vscmd, v_off, vinc;
212  int y;
213  int stride = cc->frame.linesize[0];
214  uint8_t *in = cc->frame.data[0];
215  uint8_t *out = new_frame->data[0];
216 
217  color = data[0] & 0x0F;
218  hscmd = (data[1] & 0x30) >> 4;
219  vscmd = (data[2] & 0x30) >> 4;
220 
221  h_off = FFMIN(data[1] & 0x07, CDG_BORDER_WIDTH - 1);
222  v_off = FFMIN(data[2] & 0x0F, CDG_BORDER_HEIGHT - 1);
223 
224  /// find the difference and save the offset for cdg_tile_block usage
225  hinc = h_off - cc->hscroll;
226  vinc = v_off - cc->vscroll;
227  cc->hscroll = h_off;
228  cc->vscroll = v_off;
229 
230  if (vscmd == UP)
231  vinc -= 12;
232  if (vscmd == DOWN)
233  vinc += 12;
234  if (hscmd == LEFT)
235  hinc -= 6;
236  if (hscmd == RIGHT)
237  hinc += 6;
238 
239  if (!hinc && !vinc)
240  return;
241 
242  memcpy(new_frame->data[1], cc->frame.data[1], CDG_PALETTE_SIZE * 4);
243 
244  for (y = FFMAX(0, vinc); y < FFMIN(CDG_FULL_HEIGHT + vinc, CDG_FULL_HEIGHT); y++)
245  memcpy(out + FFMAX(0, hinc) + stride * y,
246  in + FFMAX(0, hinc) - hinc + (y - vinc) * stride,
247  FFMIN(stride + hinc, stride));
248 
249  if (vinc > 0)
250  cdg_fill_wrapper(0, 0, out,
251  0, CDG_FULL_HEIGHT - vinc, in, color,
252  stride, vinc, stride, roll_over);
253  else if (vinc < 0)
254  cdg_fill_wrapper(0, CDG_FULL_HEIGHT + vinc, out,
255  0, 0, in, color,
256  stride, -1 * vinc, stride, roll_over);
257 
258  if (hinc > 0)
259  cdg_fill_wrapper(0, 0, out,
260  CDG_FULL_WIDTH - hinc, 0, in, color,
261  hinc, CDG_FULL_HEIGHT, stride, roll_over);
262  else if (hinc < 0)
263  cdg_fill_wrapper(CDG_FULL_WIDTH + hinc, 0, out,
264  0, 0, in, color,
265  -1 * hinc, CDG_FULL_HEIGHT, stride, roll_over);
266 
267 }
268 
270  void *data, int *got_frame, AVPacket *avpkt)
271 {
272  const uint8_t *buf = avpkt->data;
273  int buf_size = avpkt->size;
274  int ret;
275  uint8_t command, inst;
276  uint8_t cdg_data[CDG_DATA_SIZE];
277  AVFrame new_frame;
278  CDGraphicsContext *cc = avctx->priv_data;
279 
280  if (buf_size < CDG_MINIMUM_PKT_SIZE) {
281  av_log(avctx, AV_LOG_ERROR, "buffer too small for decoder\n");
282  return AVERROR(EINVAL);
283  }
284  if (buf_size > CDG_HEADER_SIZE + CDG_DATA_SIZE) {
285  av_log(avctx, AV_LOG_ERROR, "buffer too big for decoder\n");
286  return AVERROR(EINVAL);
287  }
288 
289  ret = avctx->reget_buffer(avctx, &cc->frame);
290  if (ret) {
291  av_log(avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
292  return ret;
293  }
294 
295  command = bytestream_get_byte(&buf);
296  inst = bytestream_get_byte(&buf);
297  inst &= CDG_MASK;
298  buf += 2; /// skipping 2 unneeded bytes
299 
300  if (buf_size > CDG_HEADER_SIZE)
301  bytestream_get_buffer(&buf, cdg_data, buf_size - CDG_HEADER_SIZE);
302 
303  if ((command & CDG_MASK) == CDG_COMMAND) {
304  switch (inst) {
306  if (!(cdg_data[1] & 0x0F))
307  memset(cc->frame.data[0], cdg_data[0] & 0x0F,
308  cc->frame.linesize[0] * CDG_FULL_HEIGHT);
309  break;
312  if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
313  av_log(avctx, AV_LOG_ERROR, "buffer too small for loading palette\n");
314  return AVERROR(EINVAL);
315  }
316 
317  cdg_load_palette(cc, cdg_data, inst == CDG_INST_LOAD_PAL_LO);
318  break;
320  cdg_border_preset(cc, cdg_data);
321  break;
323  case CDG_INST_TILE_BLOCK:
324  if (buf_size - CDG_HEADER_SIZE < CDG_DATA_SIZE) {
325  av_log(avctx, AV_LOG_ERROR, "buffer too small for drawing tile\n");
326  return AVERROR(EINVAL);
327  }
328 
329  ret = cdg_tile_block(cc, cdg_data, inst == CDG_INST_TILE_BLOCK_XOR);
330  if (ret) {
331  av_log(avctx, AV_LOG_ERROR, "tile is out of range\n");
332  return ret;
333  }
334  break;
337  if (buf_size - CDG_HEADER_SIZE < CDG_MINIMUM_SCROLL_SIZE) {
338  av_log(avctx, AV_LOG_ERROR, "buffer too small for scrolling\n");
339  return AVERROR(EINVAL);
340  }
341 
342  cdg_init_frame(&new_frame);
343  ret = ff_get_buffer(avctx, &new_frame);
344  if (ret) {
345  av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
346  return ret;
347  }
348 
349  cdg_scroll(cc, cdg_data, &new_frame, inst == CDG_INST_SCROLL_COPY);
350  avctx->release_buffer(avctx, &cc->frame);
351  cc->frame = new_frame;
352  break;
353  default:
354  break;
355  }
356 
357  *got_frame = 1;
358  } else {
359  *got_frame = 0;
360  buf_size = 0;
361  }
362 
363  *(AVFrame *) data = cc->frame;
364  return buf_size;
365 }
366 
368 {
369  CDGraphicsContext *cc = avctx->priv_data;
370 
371  if (cc->frame.data[0])
372  avctx->release_buffer(avctx, &cc->frame);
373 
374  return 0;
375 }
376 
378  .name = "cdgraphics",
379  .type = AVMEDIA_TYPE_VIDEO,
381  .priv_data_size = sizeof(CDGraphicsContext),
385  .capabilities = CODEC_CAP_DR1,
386  .long_name = NULL_IF_CONFIG_SMALL("CD Graphics video"),
387 };